The present invention relates to a weighing system for powder, and more particularly, to an automatic weighing system which provides a turn table for carrying a plurality of weighing containers.
Most weighing systems for powdery chemicals or medications are designed to automatically control the weighing and mixing of the powder to prevent from contamination of the working environment and to avoid injury to the health of the operators who are in charge of these procedures. However, an inconvenience arising from these systems is the inefficiency in conveying powder since each single carrier, for weighing interval, only can carry a single container to be weighed.
Another disadvantage of conventional powder weighing systems is that the powder collecting units thereof do not function effectively. For example, as shown in FIG. 6 of the drawings, powder outputted from an outlet of a feeding pipe 90 falls into a container 94 disposed on a plate 93 of a weighing unit 92. A dust shield 95 covers the whole weighing unit and the outlet of the feeding pipe 90 to prevent the powder from escaping into the environment, causing contamination, and to prevent undesired external dust or the like from entering the weighing system. A powder collecting pipe 96 is provided on the dust shield 95 to collect floating powder. As indicated by the arrows in FIG. 6, floating powder is carried by an air stream and then sucked away via the powder collecting pipe 96. Yet the air stream passes through the feeding powder stream and results in that powder having a smaller dimension, which should be fed into the container 94, will be carried away by the air stream, resulting in inefficient weighing. Furthermore, powder will accumulatively adhere to the inner surface of the powder collecting pipe 96 and, after a period of time, will fall into the container 94, thus affecting the accuracy of weighing. Moreover, the air stream created for carrying the floating powder is often too strong, thus affecting the weighing accuracy.
The present invention provides an improved weighing system to mitigate and/or obviate the above-mentioned problems.